SERDES Calculator

Calculate symbol rate, unit interval, Nyquist frequency, and aggregate bandwidth for NRZ and PAM4 links.

Live

Input

Data Rate (GT/s or Gbps)

Modulation

Lanes

Encoding Efficiency (%)

Symbol Rate

32 GBaud

UI: 31.3 ps

Nyquist Frequency

16.00 GHz

NRZ modulation

Parameter	Value
Bits per symbol	1
Symbol rate	32 GBaud
Unit interval (UI)	31.3 ps
Nyquist frequency	16.00 GHz
Raw aggregate bandwidth	128.0 Gb/s (16.00 GB/s)
Effective bandwidth	126.0 Gb/s (15.75 GB/s)

Example input:

32 GT/s NRZ × 4 lanes → 32 GBaud, 31.25 ps UI, 16 GHz Nyquist

Results

Engineering Notes

PAM4 and SNR

PAM4 encodes 2 bits per symbol but uses 4 voltage levels with 1/3 the amplitude spacing of NRZ. This reduces SNR by ~9.5 dB compared to NRZ, requiring more sophisticated equalization and forward error correction (FEC).

Encoding Overhead

Different protocols use different encoding: PCIe Gen1/Gen2 use 8b/10b (20% overhead), Gen3+ uses 128b/130b (~1.5% overhead), and Gen6 uses PAM4 with FLIT mode. Ethernet uses 64b/66b or 256b/257b. Set the encoding efficiency to match your protocol.

This tool is intended for engineering analysis and educational purposes. Values and interpretations should be validated against the applicable JEDEC, PCI-SIG, NVM Express, MIPI, vendor datasheet or other authoritative specification.

Frequently Asked Questions

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